Experimental investigation of heat transfer characteristics on micro-scale array jet impingement

In order to investigate the heat transfer characteristics of array jet impingement with oblong pin-fin in real engine size, experimental study was taken with the Reynolds number varying from 1000 to 10000 and the Knudsen number equal to the real working condition of engine. The arrangement of pin-fin arrays was divided into in-line and staggered. The diameter of impingement holes were 0.4mm, 0.5mm and 0.6mm, respectively. Ratios of the distance between the impingement wall and the target wall to the impingement hole diameter(H/D)were 1, 1.5 and 2, respectively. The effects of these geometries on the average heat transfer coefficient of the structure were studied. The results reveal that the arrangement of pin-fin arrays has little influence on average heat transfer coefficient of the channel. The oblong pin-fin is more likely to guide the flow than turbulent it.With the same Reynolds number when the impingement hole diameter decreases, the mass flow rate of the cooling-air decreases by 33%, but the average heat transfer coefficient drops 10% at most. The structure with smaller hole has the potential to keep the same heat transfer intensity and reduce the mass flow rate of the cooling-air at the same time. And with the same Reynolds number, the average heat transfer coefficient of the structure decreases as the H/D increases.